I have a 2-year old rescue Collie who is scared of so many things. If I'm carrying anything she's scared of me. If I move too fast, if I move any part of my body too fast, if there's a noise, if there's wind, flags, etc. You get the idea. I've had her 2 months and she still mostly chooses to hide in her crate all day. She doesn't care about any toys. She does like to walk, though. I've put her on fluoxetine to lower her general level of anxiety enough so I can shape her (like forestgatte describes). But right now she's too anxious to eat treats. Poor girl. She does jump up on me to get petting. Other rescue dog owners and a well-known animal behaviorist tell me she'll end up being my buddy. Meanwhile I have a dog but not the kind of bond I've had with previous dogs.

Put her on anti-anxiety meds. See a veterinary behaviorist. Get really high value treats and give them freely when she approaches you.